## Al Gore Rhythms [R for BE/BA]

Dear D Labes!

» Hope you have already waited for me.

» Here are the results of the SAS Proc Power.

» Seems the power is calculated in this case

Fascinating.

» My own rolled code (relying on Owens Q-functions, undocumented but available in SAS) gives:

That’s the more interesting part (homebrew)!

n=4 takes the lead by 4:3! Observations:

#5 (based on Algorithm AS 243) and #6 give identical results. This is not surprising, because the VBA-routine within FARTSSIE was written by Russell V. Lenth, the author of AS 243. #2/3 agree; for n=6 power is comparable with #5/6. #4 calculates lower power than #1-3, but still would suggest n=4. The difference between #1-3 and #5/6 might be due to different algorithms for estimating the noncentral

Maybe I should contact Dieter Hauschke to join the party…

» Hope you have already waited for me.

**Yesss!**» Here are the results of the SAS Proc Power.

» Seems the power is calculated in this case

**totally wrong**!Fascinating.

» My own rolled code (relying on Owens Q-functions, undocumented but available in SAS) gives:

That’s the more interesting part (homebrew)!

` n % power n % power`

------------------------------------------------

#1 Diletti *et al.* 4 >70 6 >90

#2 PASS 4 72.90

#3 D Labes' SAS code 4 72.9014 6 98.6992

#4 nQuery Advisor 7 4 71.559 6 97.943

#5 R-code 4 66.674 6 98.697

#6 FARTSSIE 1.6 4 66.674 6 98.697

#7 StudySize 2.0.1 4 15.9 (!) 6 93.201

n=4 takes the lead by 4:3! Observations:

#5 (based on Algorithm AS 243) and #6 give identical results. This is not surprising, because the VBA-routine within FARTSSIE was written by Russell V. Lenth, the author of AS 243. #2/3 agree; for n=6 power is comparable with #5/6. #4 calculates lower power than #1-3, but still would suggest n=4. The difference between #1-3 and #5/6 might be due to different algorithms for estimating the noncentral

*t*-distribution (#1/3: ?, #2: AS 243?, #4: AS 184, #5/6: AS 243). #7 uses approximations (Ref. 2 in this post); however, yields conservative results.Maybe I should contact Dieter Hauschke to join the party…

—

Cheers,

Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. ☼

Science Quotes

Cheers,

Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. ☼

Science Quotes

### Complete thread:

- R-Code for Power in 2×2 Cross-over Helmut 2006-12-28 21:33 [R for BE/BA]
- Power in Diletti's sample size table Helmut 2007-01-01 23:59
- Approximate Power Helmut 2007-01-06 15:17
- Power Calculation for replicate crossover design mathews 2008-04-03 13:19
- Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
- Power Calculation for replicate crossover design mathews 2008-04-04 13:21

- Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
- Exact Power Helmut 2009-09-25 19:20
- Exact Power ElMaestro 2009-09-27 23:27
- Software validation Helmut 2009-09-28 15:21
- All the important answers are here! ElMaestro 2009-09-28 19:12
- All the important answers are here! Helmut 2009-09-28 19:52
- All the important answers are here! ElMaestro 2009-09-28 20:18
- All the important answers are here! yjlee168 2009-09-28 21:30
- All the important answers are here! Helmut 2009-09-28 23:18
- 42! SASophylistic power oracle d_labes 2009-09-29 13:37
- Al Gore Rhythms Helmut 2009-09-29 14:52
- Al Gore Rhythms ElMaestro 2009-09-29 18:14
- Al Gore Rhythms yjlee168 2009-09-29 23:55

- Al Gore Rhythms Helmut 2009-09-29 14:52

- 42! SASophylistic power oracle d_labes 2009-09-29 13:37
- All the important answers are here! yjlee168 2009-09-29 23:49

- All the important answers are here! Helmut 2009-09-28 23:18

- All the important answers are here! Helmut 2009-09-28 19:52

- All the important answers are here! ElMaestro 2009-09-28 19:12

- Software validation Helmut 2009-09-28 15:21

- Exact Power ElMaestro 2009-09-27 23:27

- Power Calculation for replicate crossover design mathews 2008-04-03 13:19

- Approximate Power Helmut 2007-01-06 15:17
- R-Code for Power in 2×2 Cross-over KDA 2019-01-23 04:24
- R-Code for Power in 2×2 Cross-over Ohlbe 2019-01-27 18:24

- Power in Diletti's sample size table Helmut 2007-01-01 23:59